PSYB01 - Chapter 14
External validity-extent to which findings may be generalized .
College students -students make up most of the experiments .
Students as a group are more homogeneous than non-student samples meaning students are
more similar to each other than adults are similar to other adults in the general population .
College students are less conservative and rated women and ethnic minorities more favorably
showing DIFFERENCES in students and adults
Like white rats, students are cheap and easy to obtain .
Volunteers - they differ from non-volunteers .
They are more highly educated, higher SES, more in need of approval and more social .
Titles of studies also influences who signs up .
Internet Research - computers are used in certain demographics .
General considerations- gender bias ex. using only women for contraception studies .
Solution is to be aware of possible gender differences and include both males and females in
Also should recognize how males and females may differ interpret independent variable
manipulations or questions asked in a questionnaire .
Locale-the location that Ps are got from can have an impact on a study’s external validity .
Ex. students at UCLA may differ from students at a nearby state uni .
People in Iowa are different from people in NYC .
Extraversion varies from state to state .
Generalization as a statistical interaction- the problem of generalization can be thought of as an
interaction in a factorial design .
Interaction occurs when a relationship between variables exists under one condition but not
another, or when the nature of the relationship is different in one condition than in another .
Ex. A study examines the relationship between crowding and aggression among males and
reports that crowding is associated with higher levels of aggression. You may then question
whether the results are generalizable to females .
Questioning the generalizability of a study that uses only one DC (males), you are suggesting
there's an interaction between gender and the IV .
If no interaction, the males and female results will be identical so the original study can be
generalized to females .
No interaction but males results are displaced higher, there is generalization because overall
relationship is present .
Interactions will have completely different results of in opposite directions, so the original male
results CAN'T be generalized to females .
Aspects differ across cultures Ex. Asians benefit more from support that comes with the comforts of proximity to friends
rather than sharing .
Aspects are similar across cultures
Low waist-to-hip ratio along females were seen as attractive across some cultures- so results
were generalizable .
Generalizing To Other Experimenters
- Any influence the experimenter has on subjects is constant throughout the